Semiconductor processing involves deposition, patterning and removal of various layers of materials on semiconductor wafers.
A typical semiconductor processing method 1000 is shown in FIG. 1. Usually, wafers are processed in a track-like setup (often referred to as the “wafer track”) that integrates several instruments needed to process photo resist. Frequently, after deposition of a photo resist layer, block 1002, it is necessary to planarize the deposited layer using chemical mechanical polishing (CMP). CMP involves abrasion of the layer with a polishing pad, in the presence of a slurry. Following the completion of the CMP, the slurry debris and contaminants must be removed to avoid contamination of integrated circuit layers. After the photo resist deposition, the wafer is removed from the wafer track and is placed in a scanner.
The scanner is a projection-printing tool whereby an image of a mask is projected onto the wafer. The image of the mask is projected onto the wafer, exposing the main field of the wafer, block 1004. Following the main field exposure, the edge of the wafer is exposed in a wafer edge exposure (WEE) unit, forming an edge sealing ring, block 1006.
Scanner exposure time is often a time limiting factor in many semiconductor processing methods.
After scanner exposure is completed, the wafer is then returned to the wafer track for pattern developing, block 1008.